Printed circuit lamp base



June 30, 1959 D. A GROVEMILLER ET AL 2,892,992

PRINTED CIRCUIT LAMP BASE Filed Feb. 4, 1957 lnvenfior's: DaLe A. GfovemiLLev, Joseph Kas' teLic,

5 Their Afio nes.

United States Patent 2,892,992 YPRINTED CIRCUIT LAMP'BASE Dale A. Grovemiller and Joseph Kastelic, Euclid, Ohio, assignors to General Electric Company, a corporation of New York Application February 4, 1957, Serial No. 637,929 3 Claims. (Cl. 339-145 The present-invention relates to lamp bases generally and more particularly the invention relates to bases for miniature electric lamps of the low voltage type used for illumination of instrument panels for automobiles, air planes and the like. 7

"A'type of instrument panel now in use particularly for automobiles includes a printed electric circuit in which power for the instrument panel lamp is supplied through a pair of opposed arcuate metal contacts secured in spaced positions to the back of the panel around a keyhole opening through the panel. In mounting the lamp on the panel the bulb thereof is passed from the back to the front of the panel through the opening.

At present, an adapter is used to removably secure a miniature electric lamp provided with a bayonet type base to the panel and to connect the shell and center contacts of the lamp base with the arcuate contacts of the printed circuit. Such adapters inherently add to the cost of such installations because they must be separately manufactured and in mounting the lamp on the panel the lamp must first be mounted in the adapter and the adapter then mounted on the panel. 9 Both the adapter andvthe mounting of the lamp therein add considerably to. the cost of making original installations of such lamps on such panels.

"The principal object of the present invention is to provide a lamp having a base adapted for mounting on instrument panels of the above type. Another object of the invention is to provide for such a lamp an inexpensive three part base of simple, rugged structure readily manufactured by mass production methods. Further objects and advantages of the invention will appear from the following detailed description of a species thereof, from the accompanying drawing and the appended claims.

""In accordance with the above objects the base embodying 'thelpresent invention is made up of a single thick 'walled hollow shell of electrically insulating, organic plastic molding material and a pair of metal contact strips molded in the wall of the shell so as to be completely and firmly embedded therein except for portions at the opposite ends of the strips which portions are exposed and suitably positioned on the outside of the shell for making electrical contacts with the panel contacts on one hand and for being electrically connected to the lead-in wires of the lamp on the other hand.

In the drawing'accompanying and forming part of this specification an embodiment of the invention is shown inwhich:

, Fig. 1 isa perspective view on an enlarged scale of a lamp base embodying the invention.

Fig; 2 is an elevational, partly sectional view of the base shown in Fig. 1 with the section taken along the line 2,- 2 of Fig. l in the direction of the arrows, with a lamp envelope shown in full lines mounted in and connected to the base and with the panel for receiving the based lamp indicated in broken lines.-

,Fig. 3 is an elevational view of the based lamp shown ice in Fig. 2 rotated 90 from the position thereof shown in Fig. 2, and

Fig. 4 is a fragmentary view of an instrument panel for the lamp shown in Figs. 2 and 3. 7 Referring to the drawing, the lamp illustrated in Figs. 2 and 3 includes a sealed light transmitting glass envelope 1 of spherical shape provided with a neck 2. A pair of inlead wires 3 and 4 extend through the wall of the neck and, as shown in Fig. 2, the envelope 1 is pro vided with a sealed exhaust tip 5 on the neck 2. Lamps having envelopes of this type are well-known in the art as lamps of the butt-seal type and since the internal structure of such lamps, which includes an incandescible filament to the opposite ends of which the inleads 3 and 4 are electrically connected, is well-known in the art and forms no part of the present invention, the internal structure has been omitted from the drawing for simplicity of illustration.

The lamp also includes a three-part base embodying the invention and which, as shown in Figs. 1, 2 and 3, is made up of a molded plastic, electrically insulating, generally cylindrical, thick-walled shell 7, open at one end and closed at the opposite end, and two bent, flat metal electrically conducting strips 8 and 9, such as phosphor bronze strips, the centerportions 10 and 11 of which extend an appreciable distance longitudinally of the shell 7 and are firmly embedded in diametrically opposite positions in the cylindrical wall of the shell to form a unitary, electrically conducting lamp base. The end portions 12, and 13, 14 and 15 of the strips 8 and 9, respectively, are exposed outside the shell 7 for engagement with power supply contacts and for connection with the lamp inlead Wires 3 and 4, as described below. While the sell 7 may consist of any suitable thermoplastic molding material, such as methyl methacylate, or thermosetting plastic molding material, such as phenol, urea and melamine formaldehyde and alkyd type plastic, a thermosetting phenol formaldehyde type plastic is preferred.

The base and the envelope of the lamp are fastened together by a ring 16 of conventional lamp basing cement which closes the space between the neck of the envelope v passage of the spherical part1 of the lamp envelope and two diametrically spaced slots 20 and 21 for the passage of holding members provided on the lamp base as described later herein. The panel 18 also includes a pair of spaced arcuate shaped electrical contacts 22 and 23 fastened to the back surface thereof around the circular portion 19 of the keyhole opening and angularly spaced from the slots 20 and 21. The contacts 22 and 23 are connected to opposite terminals of a power source (not shown) for a lamp mounted on the panel.

For mounting the lamp on the panel the base shell 7 is provided with an outwardly extending annular flange 25 at about the longitudinal center thereof which flange is of larger diameter than the circular portion 19 of the keyhole opening in the panel 18. The cylindrical portion 26 of the base shell 7 between the flange 25 and the bulb receiving open end 27 of the shell is slightly smaller in diameter than the circular part 19 of the keyhole opening and is of such length with respect to the depth of the keyhole opening through the panel that the spherical part I of the envelope of a lamp mounted 3. onthe panel 19 projects, from thepanel when the lamp is mounted thereon with the flange engaging the back of the panel around the keyhole opening, as shown in Big-T The base shell 7 is also provided with a pair of integral holding tabs or cars 28 and29-extending outwardly in diametrically opposite directions from the end ofthe saidi cylindrical portion;26..ofi the shell 7 and spaced longitudinally along the shell from the flange 25 a .sufii: cient' distance; to engage-.the front of the panel 18 when the-flange 25- is inengagement with-the back of the panel.

The lamp is removably-mounted on, the panel 18 bypassing the spherical. part 1, of ,the envelope through the keyhole opening; 19 and the cars 28 .and 29 through theslots 20 and 21,1pressing the flange 25 against the back ofthe panel 18 and then rotating the lamp to bring the, ears 28 and 29 into engagementwith the front of the panel. The panel is conveniently provided with grooves .30.and 31. adjacent the slots- 20. and. 21 to re ceive the ears 28 and 29 and the base shell 7 is provided with longitudinally extendingribs between the sides of the ears 28 and 29 and the flange-25 to limit rotation of the lamp in the panel. Oneof such ribs v33 is shown in Fig. 1 of the drawing.

When. the lamp is so mounted on the panel, the bent metal. strips 8 and 9 engagethe contacts 22 and. 23 on the panel and conduct current. to the inlead wires 3 and 4 of the lamp as shown in Fig. 2. For this purpose the strips 8 and 9 are bent-in such manner that the exposed end portions -12 and 14, respectively, which make wiping electrical contact with the panel contacts 22 and 23, respectively, on rotation of the lamp when mounting the lamp onthe panel. as described above, extend outwardly in diametrically opposite directions from the shell 7 and overlie the flange 25 in part so as to be partially supported by the flange against the panel contacts 22 and 23. The opposite ends 13 and -15 of the strips 8 and9, respectively, which are bent so as to extend transversely inward of the shell 7 at the closed end of the shel'l,are exposed in part at the end of the shell and are provided with openings in the formof eyelets 34 and 35 at their exposed portions.

The closed end of the shell has an integral. wall 36 (Figs. 2 and '3) provided withconical openings 37 and 38. The openings in the eyelets 34 and 35 on the strips 8 and 9, respectively, communicate with the openings 37 and 38, respectively,.in the wall 36 to define passages therewith from the interior to the exterior of. the base and through which passages the leading-in wires 3 and 4 of the lamp are threaded in the usual manner in assembling the base and the lamp envelope. The inwardly directed end portions 13 and Y15 of the strips 8 and 9, respectively, are exposed on the bottomof the base shell '7 to facilitate" soldering of the cut ends of the threads wires 3 and 4 to the eyelet parts 34 and 35 of the strips. InFig. 2 of the drawing, the ends. of the wires 3 and 4 are shown soldered to the strips at 39 and 40.

The bottom wall 36 of the base shell7 has thereon an outwardly protruding embossment 741' V-shaped in cross section and extending across the center ofvthe wall 36-and between the spaced apart, exposed end portions 13 and 15 of the strips 8=and 9.- The embossment 41 prevents'the soldershown at 39- and 40 from running between the said strip end portions 13 and 15 during the.

soldering operation and short-circuiting of the lamp filament in an assem bledlamp. The embossment also serves topreventan accidental short circuit during use of the.

lamp. 7 The sides of' the shell 7 at the ends of the em: bossment and between the flange" 25 and the vWall 36 are fiat' to facil-itateywiththe'embossment, mounting the lamp inithe panel opening by providing a finger. grippable portion on -theshell-which-' facilitates turning of the lamp-in the panel opening toengage the lamp base with the panel. This portion of the shell 7 thus is of a flattened cylindrical shape, as shown in Figs. 1 to 3.

The bottom wall 36 of the shell 7 is also provided with a conical cavity 42 opening toward the interior of the shell at the center of the wall and extending into the embossed portion of the wall 36- to accommodate the exhaust tip 5 of the lamp envelope 1 as shown in Fig. 2. The strips 8 and 9 terminate'andm-are firmly embedded in the embossed portion of the wall 36, as shown in Fig. 2.

The ends 12 and 14'of the strips 8"an'd9, respectively, engaging the panel contacts 22 and 23 areprovided with raised embossedportions 43 and 44 on -the side thereof facing in the direction of the envelope receiving end 27 of the base to provide an area at which a high unit contact pressure is obtained with the panel contacts. The portions 43 and 44 are slanted as shown in Fig. 1 to facilitate rotation of the base in one direction only in the panel 18 to move the tabs 28--and 29 into the grooves 30 and 31 and hold the base in that rotated position.

The base described above is readily fabricatedby mass production methods, the three parts thereof being capable of beingmolded together in a single operation.

While a species of base embodying the invention has been shown and. described it will be understood that changes may bemade in the form and details thereof without departure from the spirit of the invention and within the scope of the appended claims.

What we claim as new and desire to secure by Letters Patent of the United States is:

1. A lamp base comprising a thick-walled cylindrical molded shell of organic plastic electricallyinsulating material open at one end for attachment to a lamp envelope having an outwardly extending neck terminating in an exhaust tip and a pair of in-lead wires extendingfrom said neck, the opposite end of said shell being closed by an integral end wall having an outwardly protruding.ernhossmerit extending across its center and having at its centeran inwardly opening cavity for. receiving. the end of said lampneck, said end wall havingalso a pair of openings therethrough diametrically opposed with respect to said cavity and on opposite sides of said embossment, said base comprising also a pair of conducting 'strips having portions thereof betweenthe end portions completely embedded in the cylindrical wall of said shell and-extending longitudinally of said base from said end wall toward the open end of said shell, portions of said conducting strips adjacent said end wall being bent inward at said end wall and exposed on the bottom of said base in the region of said end wall openings and having eyelet shaped openings. communicating with said end 'wall openings to provide passages for threading the inlead wires through said base,

the opposite end portions of said contact strips being exposed and extending transversely" outward in opposite directions from the cylindrical wall of said shell for en-" gagement with electrical supply contacts for the lamp and having slanted raised embossments on their contact engag:

ing surfaces.

2. A lamp base comprising a thick-walled cylindrical molded shell of organic plastic electrically insulating ma terialopen'at one end for attachment to a lamp envelope having an outwardly extending neck and a pair of inlead wires extending from said neck, the opposite end of said shell being-closed by an integral wall'having a pair of spaced openings therethrough diametrically opposed with nicated with said end wall openings to provide passages for threading the lamp inlead wires through said base, said eyelet-shaped openings defining cavities for accommodating solder for securing lamp inleads to the contact strips, said end wall having an outwardly protruding embossment extending across its center and between the spaced openings in said end wall for separating the pools of molten solder in said eyelet cavities during soldering of the lamp inleads to said contact strips, the opposite end portions of said contact strips being exposed and extending transversely outward in opposite directions from the cylindrical wall of said shell for engagement with electrical supply contacts for the lamp.

3. A lamp base comprising a thick-walled cylindrical molded shell of organic plastic electrically insulating material open at one end for attachment to a lamp envelope having an outwardly extending neck and a pair of inlead wires extending from said neck, said shell having an internal shoulder at the open end thereof for retaining a ring of basing cement at said end, the opposite end of said shell being closed by an integral wall having a pair of spaced openings therethrough diametrically opposed with respect to the center of said wall, said base comprising also a pair of conducting strips having portions thereof between the end portions completely embedded in the cylindrical wall of said shell and extending longitudinally of said base from said end wall toward the open end of said shell, portions of said conducting strips adjacent said end wall being bent inward at said end wall and exposed on the bottom of said base in the region of said end Wall openings and having eyelet-shaped openings communicated with said end wall openings to provide passages for threading the lamp inlead wires through said base, said eyelet-shaped openings defining cavities for accommodating solder for securing lamp inleads to the contact strips, said end wall having an outwardly protruding embossment extending across its center and between the spaced openings in said end wall for separating the pools of molten solder in said eyelet cavities during soldering of the lamp inleads to said contact strips, the opposite end portions of said contact strips being exposed and extending transversely outward in opposite directions from the cylindrical wall of said shell for engagement with electrical supply contacts for the lamp.

References Cited in the file of this patent UNITED STATES PATENTS 1,633,827 Siegel June 28, 1927 2,033,748 Wallace Mar. 10, 1936 2,615,950 Lamb Oct. 28, 1952 2,741,747 Woofter Apr. 10, 1956 

